Create blue roses with RNAi technique

The 2006 World Rose Conference was held in Osaka City from May 11-17, 2006. In the conference, the organizers presented many new and beautiful roses varieties. However, the most outstanding feature of this conference was the blue rose created by RNAi technology due to the cooperation between scientists of Florigene and Suntory under the technical assistance of the Science Institute. Australian Technology (SCIRO). Green roses can be considered as the Holy Grail of rose breeders since 1840. At that time, the British and Belgian gardening associations have awarded 500,000 francs to the first person to create roses. green Blue.

The molecular geneticists of Florigene and Suntory have won this award, an award that has dampened many traditional rose breeders by incorporating a few old elements, a few weak new elements, a few elements of borrowed shoulders and finally a few elements that create blue. The element that creates the green color on the rose is the delphinidin gene that Florigene's geneticists clone from the rose flower (Viola x wittrockiana) to directly synthesize the green on the rose tree. The shoulder factor borrowed is the iris gene to create the DFR (the dihydroflavonol reductase) enzyme, which will complete the cycle of delphinidin fusion on roses. The new element is an artificial gene. This gene was created by the Suntory group of geneticists with a new technique called RNA interference, abbreviated RNAi. This technique was consulted by the CSIRO institute to turn off the activity of the red-forming gene in roses. It was this gene that defeated the efforts of the Florigene team to activate the delphinidin cycle in roses for almost a decade. That's why Suntory scientists created a 'silent' gene to overcome this difficulty with RNAi technology. RNAi technology is a new direction in biomedical research over the past 25 years.

Dr.Peter Waterhouse's research team at CSIRO Institute, Canberra, Australia pioneered the use of RNAi technology for the discovery and application of gene functions in plants. Although the morphology of the rose is light in lilac, it is the first rose in the world to be genetically engineered to produce green roses that actually bridge the formation of the color spectrum on roses from The blue color changes to Mediterranean blue or even blue. So it can be said that this is the first commercial flower in the world formed by RNAi technology. Florigene's green rose is a foreshadowing of a bright future for plant breeders in the 21st century.

How is blue rose created?

In plants there is a molecule called anthocyanin that is considered to be the dominant pigment in flowers, fruits and other cell tissues. Usually the main colors of flowers originate from anthocyanins in the presence of a few yellow carotenoids. In addition, anthocyanin dihydrokaempferol (DHK) is an enzyme that governs all three pigmentation processes in plants including cyanidin, pelargonidin and delphinidin. The cyanidin gene encodes an enzyme that modifies DHK enzymes to form the cyanidin cycle leading to the expression of red, pink or mauve. While the delphinidin gene, which is not present in rose plants, encodes a fairly similar enzyme for changing DHK enzymes to form the color synthesis according to the delphinidin cycle. Another type of enzyme called dihydroflavinol reductase (DFR) will support colors that show you in all three cycles (Figure 1). This enzyme is very important because without it it will not be able to color on the petals. Therefore, DFR mutations produce white flowers. In the rose there is no delphinidin gene to form color according to its cycle. The delphinidin cycle can form red or green in flowers under the influence of DRF and pH.

The anthocyanin synthesis cycle diagram shows the role of dihydrokaempferol and the three cycle branches that form different colors. The red frame is the delphinidin cycle that contributes to the formation of green on roses. (Photo: Florigene)

During the 20th century, rose breeders created a series of exotic flowers such as lilac roses or gray roses that were considered a stepping stone to creating blue roses. However, they are rare variants of the cyanidin cycle. So swimming, we can understand why the traditional breeding cannot produce the green roses as expected because the genetic rose does not have the gene to create the delphinidin cycle. Therefore Florigene scientists took a very long step by cloning the delphinidin gene from the petal flower in 1991. In the mid-1990s scientists had the perfect technique for breeding. roses and flowers from tissue culture cell lines. Also during this period, Florigene had the first red rose rose made from the delphinidin gene called 'Cardinal'. The combination of the cyanidin gene and the delphinidin gene produced an impressive purple burgundy variety. Of course it is not blue but technically it is a huge step forward.

So to create a blue rose, Florigene researchers needed a white rose in which the DFR gene was inactivated. Researchers of Florigene company often consult with TS's research team. Peter Waterhouse at CSIRO Institute, Australia. In 2001 Dr. Waterhouse discussed the use of RNAi technology to inhibit a desired gene that could later be replaced by another gene. So the scientists of Florigene company

immediately realized the benefits of using RNAi technology to inhibit DFR activity in red roses leading to inhibition of the cyanidin cycle and then delferidine with a completely new DFR gene to complete the cycle. synthesis of delphinidin in roses. At the same time, researchers from Suntory Co., Japan, had the same idea by using RNAi technology to inhibit DFR gene and then clone a new delphinidin gene from pansy and DFR gene. from iris flowers. DFR genes of roses and iris are quite similar and share many DNA codes but RNAi technique is also very delicate because it can inhibit the DFR gene of roses without affecting the DFR gene of iris by The creation of a gene-suppressive structure has the effect of producing hairpin dsRNA molecules (hairpin dsRNA) with the sequence of homology with the DFR gene of roses.

So to create a blue rose, Suntory scientists applied a set of three genes. An artificial gene is used for RNAi technology to inhibit the DFR gene of roses, which makes roses not show color. After that, delphinidin gene from pistil and DFR from iris will produce roses with very high delphinidin content in the petals (Figure 2). However, it must be noted that one factor affecting the green color on the petal is the cell pH and that is one of the main reasons why the flowers have the same anthocyanin cycle but have different colors. . When cell pH levels are alkaline, the anthocyanin pigments often become greener. Soil pH does not affect or affect very little pH of petal cells. The pH of petal cells is often genetic. Rose petals usually have a pH of about 4.5, so to create rose petals with low pH levels is very limited. So scientists thought about gene inhibition techniques using RNAi technology to identify genes that affect the acidity of the petals or adjust the petals color in other directions.

The process of forming a blue rose with the help of RNAi technology.
(Photo: CSIRO)

Blue rose is one of the products created by the application of RNAi technology. This is one of several applications of RNAi in biomedical research and is a very useful tool for understanding and exploring the mysterious functions of genes in the post-genomic era (post-genomic era).